Achieving Outstanding Absorption Performance in Electromagnetic Interference Shielding via Improving Impedance Mismatch: Sandwiched PP/CaCO₃/Ground Tire Rubber/MWCNT Composites

In this research, we present a cost-effective and environmentally friendly sandwiched structure for electromagnetic interference (EMI) shielding. This composite consists of three layers of PP/CaCO3 matrix, each containing varying concentrations of ground tire rubber (GTR) and multiwalled carbon nanotubes (MWCNTs). This design amplifies impedance mismatch across interfaces, resulting in exceptional electromagnetic wave absorption (up to 80%) and outstanding total EMI shielding effectiveness (EMI SE) of 55.2 dB. Moreover, incorporating 25 wt % recycled rubber in this composite contributes to a better mechanical performance, achieving a tensile strength of about 25 MPa and a strain of 8%, while reducing MWCNT usage by up to 65% compared to the previously studied homogeneous composite with the same thickness. This innovative approach offers a highly efficient strategy for achieving absorption-dominated EMI shielding, particularly suitable for applications such as flooring laminates where both mechanical properties and cost-effectiveness are paramount.